Pneumatic tire



Dec. l5, 1931. A. H. sH'oEMAKER PNEUMATIC TIRE Filed Aug. 9, 1928INVENTOR /l/B/? ff. /zoema'er r m/ min n l l l l il Patented Dec. 15,1931 AUNITED STATES ALVIN H. SHOEMAKER., OF SEATTLE, WASI-IINGrION I iPNE-uname TIRE Application filed August 9, 192.8. Serial No."29 8,462. I

My invention relates to improvements in pneumatic tires and the objectof my invention is to provide means on the inside of the tirecasingvvhich Will tend to flatten the tread portion of the tire casingwhich comes in contact With the road, thereby bringing into use moretread surface, increasing the durability of the tire, increasing thestability of the tire Without detracting from the resiliency of the 10same, distributing the road shock over a Wider' tread area and tendingto reduce the flexing of the cords around the sides of the tire in theregions Where the tire leaves the ground and Where the cords aresubjected to the greatest llexing.

1 The usual pneumatic tire is made of approximately cylindrical shape onthe inside and when it is inflated the'tendency of the internal airpressure is to cause the interior of '20 said tire to assume the shapeof a true circle. It the thickness of the casing throughout the treadportion is uniform then the tread will also tend to assume the shape ofatru'e circle and the tendency Will be for a very narrow portion of saidtreadto come in Contact With the road and for the central portions ofthe tread to take the greatest Wear, the side portions of the treadJrurther removed from the medial plane coming in contact With the roadonly as the tire is flattened. It is desirable to have a relatively Wideportion of the tread come in contact With the road to assure moreWearing surface and more tractive surface and to give greater stability.In attempting to give the tire a flatter tread portionit is now commonpractice to build up the tread more nearly square on the outside of thecas- Y ing by thickening the tread materia-l toward the sides of thetire and then tapering or shouldering the thickened tread portions oillabruptly so that they merge With the side Walls of the tire. This methodof obtaining a flattened tread portion by building the same up more orless flat in crosswise directions on the outside of the tire has certainundesirable features. One undesirable feature is that it leaves thetread thinnest in the medial plane of the tire Where the tread issubjected to the greatest Wear. Another undesirable feature is that itlocalizes the maximum flexing of the reinforcing cords'of'tlie tire ator :nea-r the termination of the thickened edges of the tread thuspredisposing the tire to' Ifailure at this location. f

In accordance With -my invention I- overcome the objections abovepointedout by providing means Within the tire for causingthe treadportion of a tire casingof uniform thickness to assume a flattenedcondition-` Whenit is subjected to internal air pressure.

In the drawings Figure l is a vieW incross section, with parts 'shown inperspective, of a tire casing 'constructed inv-accordance with myinvention. l f

Fig. 2 is a fragmentary cross section ofa. tire and inner tubein Whichmy invention is incorporated in the inner tubeand the tire casing is ofstandard construction.v Y

LikeV referenceV numerals `designate `like parts throughout theseveralfviev'vs. f

In Figure l, I show a tire" casing 5, l1av` ing reinforcing cords 6embedded therein-and connected vwith non-elastic rings 7 ini the beadportions vof the tire. In accordance with my invention I provide on theinside 'i5 of the tire on opposite sides ofthe medial plane of the tiretvvo spaced apart parallel ribs or bead ridges 8 Which are continuousand extend entirely around the tire'. These bead `ridges are in the'natureof thickened 8`0\ l portions of material and may be integral withthe casing, or attached tof'the casing,l or separablefrom'. the casingand may be varied in shape and size depending on'the degree'or amountyof'frlattening -Whichf it is Si? desired to impart to the treadlportionof the casing. In Figure 2 I showthese bead j j ridges 8 asembodied in and made" apart of an inner tube 9 Which may be placedvvith-v y in a tire casing 10 of ordinary construction.l E@

VIn the operation of tires embodying my invention, the internal'airpressure,V Wheny the tire is inflated,v is exertedequ'ally against allportions of theinner Wall of the 'tire' and willv tend to cause saidinner vvall to as`V g@ sume an arcuate shape.V This will betr'u'eadjacent/parts of the casing outv'vardlyfljmi l against the cords thustending to force the cords outwardly at the loca-tion of the beads, andproducing a squaring eect of the whole tire. This tends to straightenout or flatten,-

and more satisfactory performance in gen'- eral. Y f Y When the casingis constructed for use in combination with the bead ridges then saidcasing may be molded to the squared shape shown in the drawings, but, ifsaid casing yis molded of the usual substantially circular crosssectional shape and the beads 8 are used therein then said circularcasing will be caused to assume the squared shape with the flattenedtread portion as soon as it is inflated. VBy employing myinvention it ispossible to make the tread portion of the casing of substantiallyuniform, thickness and yet have said tread portion latened to aordrelatively Wide and even contact on ,the road. It is also possiblevltoavoid excessive fleXure of the cords at the sides where the-tread mergeswith the side walls of the tire, which is substantially atfthe locationof the beads 8. y

I find from actual tests that the use of the i beads not only produces aflattening of the tread portion of the tire but also produces acorresponding flattening of the side walls of the same. The dotted lines1l in Fig. l

indicate the approximate positions which the side Walls and treadvof thetirevwould assume if the beads 8 were not used therein.v

Obviously changes in form, shape and arrangement of the invention may bemade within the scope and spirit' of the lfollowing claims.V i

Claim; ,j` i il l. The combination with a tire, of parallel `Vand spacedsubstantially equal distances on opposite sides of the media-1 plane ofthe tire and arranged to'be forced outwardly by internal air pressurethereby reducing the spaced apart annular beadsridges of pliable andelastic material wit-hinisaid tire arranged to producea flattening ofthe external tread portion of the 'tire casing when the tire isinflated. Y 'Y e j2. The Ycombination with a pneumatic tire of means foriiattening the external tread p portion of said tire transversely,embodying two. spaced apart annular bead ridges of pliable and elasticmaterial formed as an integral part of the air tight lining of said Ytire and Vadapted to be forced outwardly by internal air pressure gtoimpart `a flattening effect to the tread por-tions between said ridges.

' 3.- The combination with a pneumatic tire, having a tread' of.substantially uniform thickness, :of means for flattening the eX-ter-nal'portion of-said tread'crosswise em-v bodying two parallelannular Vbead ridges vof flexible material disposed within the 'tirevdie.;

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